Applied Mechanics and Materials Vols. 204-208

Abstract: Based on the real construction technology, process and environment of Yuquanxi Bridge, the finite element method was applied in the research to make sure the crack mechanism and find out the impact of improper construction procedure on cracks of Block No.0. By comparing the numerical results with actual cracks condition, the impact of improper construction procedure on cracks of Block No.0 is uncovered clearly and it proves that to master of correct construction procedures and methodology is of great importance in construction a bridge.

Abstract: This research focuses on investigating the high performance concrete durability containing slag with different fineness and dosage. For this purpose, the 28-day compressive strength, chloride ion penetration, and frost resistance were investigated, with slag surface area 420m2/kg, 530m2/kg, 610m2/kg, and 720m2/kg, and replacement percentage 0%, 20%, 40%, and 60%, respectively. It was found that chloride ion penetration resistance were affected by the fineness and dosage of slag, and concrete frost resistance property was mainly controlled by dosage of slag rather than the fineness, and the 28-day compressive strength increased with slag incorporation.

Abstract: The experiment uses the Shenyang northern sewage treatment plant two sink the pond sludge was the indigenous Thiobacillus enrichment culture, through the matrix of different proportion, to find the most suitable matrix proportion, so as to shorten the bioleaching process start time, improve the bioleaching process for heavy metal removal efficiency. By usihng the method developed by mixing S bacteria predominantly mixed bacteria liquid, will raise the mixed strain cycle was shortened to 11 days, the best ratio of S, Fe2+ matrix is determined as 3 : 1, the matrix culture mixed Thiobacillus is faster, and can greatly improve the bioleaching boot efficiency. Fe2+ dosing is able to activate the bacterial Fe2+ enzyme synthesis, be helpful for accelerating thiobacilli on s oxidation using elemental sulfur, while also promoting microorganism to use Fe2+. Using the technology of biological leaching experiment on heavy metal removal rate is higher, compared with a single strain has more engineering application and popularization value.

Abstract: In order to protect Chinese ancient building, steel components were considered to strengthen its tenon-mortise joints and the strengthening effects were studied by shaking table tests.Based on actual sizes of an ancient building,a wooden frame model with a scale of 1:8 of the prototype structure was built considering Yan-wei type of tenon-mortise connections.Steel components were used to strengthen tenon-mortise joints of the model to enhance its stability.By white noise excitation values of basic frequency for model in both strengthened and unstrengthened conditions were obtained;By inputing El-Centro earthquake waves of different peak acceleration values,responses of displacement and acceleration for typical nodes of the model were obtained.Results show that after its tenon-mortise joints are strengthened by steel components, basic frequency of the model increases;Under earthquake the strengthened model responds with smaller peak displacement and acceleration values;With the increase of earthquake intensity,the steel components tend to perform better.Thus the steel components are effective for strengthening tenon-mortise joints of Chinese ancient buildings.

Abstract: In order to conduct the reliability analysis of frame structure, the limit state function was first fitted by artificial BP neural network. Then considering the orthogonal array method, sample data was arranged. After that an improved network modes was trained for the probabilistic analysis on a wide range data with the Monte-Carlo method. The mean and standard deviation for the limit state function was easily obtained and the reliability index on the structure can be also calculated. Finally, the example indicated that this method used in the reliability analysis for frame structure was feasible.

Abstract: For premixed pump concrete, this thesis analyzed the causes of cracks according to the relevant construction features; meanwhile, it proposed the countermeasures on structural cracks in terms of raw materials and construction technologies, thus this thesis gave certain guidance on prediction and control of such cracks.

Abstract: Influence of diaphragm parameter on stress amplitude and fatigue damage of diaphragm details were investigated based on Tai Zhou Yangtze River Bridge. FEM of steel bridge deck and diaphragm detail were established. Boundary conditions of the diaphragm details FEM were interpolated by sub-model method, and the accurate local stresses of diaphragm details correspond to different lateral distribution of wheels were calculated. Results show the stress amplitude of diaphragm details reach maximum when wheel off-center position is 150mm, and it decreases with the increase of wheel off-center position greatly. The stress amplitude of diaphragm details increase with the increase of the distance of diaphragms, and increasing diaphragm’s thickness can improve fatigue stress of steel bridge deck.

Abstract: A comparative study among five methods to calculate the structural stress of the trough to deck plate joint in orthotropic steel deck was carried out. The five methods used are surface stress extrapolation method (SSE), Haibach method, Xiao and Yamada method and CAB method. FEM analysis shows the five methods are mesh sensitive. Structural stress calculated using element type solid95 is larger than that of solid45. For fine and medium mesh model, structural stress calculated by Haibach method is larger than other methods, which means a lower fatigue life. Structural stress calculated by Yamada method is lower than other methods, which means a higher fatigue life than that calculated by other methods. For coarse mesh model, structure stress calculated by quadratic extrapolation method is larger than other methods, and, structural stress calculated by Yamada method is much lower than other methods.

Abstract: The mechanical properties of artificial frozen soils are the key for application of artificial ground freezing, (AGF) especially the creep characteristics of artificial frozen clay when a deep shaft is sunk by using AGF. Many catastrophic accidents took place in clay strata in deep freezing shafts past because of freezing tube breaking and flooding through ice wall caused by large creep deformation of ice wall. A new creep constitutive equation with separated variables for artificial frozen clay, after C. C. Vialov, is presented on base of testing data of most kinds of artificial frozen clay under the condition of drained system. On base of the new equation, a space-time- dependant design method, a modified C. C. Vialov’s, is proposed and has been successfully used for ice wall of deep shafts all over China since 1996. Finally, the stability of ice wall for deep shafts can economically and efficiently be controlled by adjusting the variables of temperature T, un-supported height h and time elapsed t according to their sensitivity or influence.

Abstract: Time dependency of chloride transport has been studied and an improving model for predicting the apparent chloride diffusion coefficient has been proposed. A probabilistic-based durability analysis to estimate failure probability on the chloride ingress into concrete has been carried out. Results of the analysis demonstrate that the improving model in this paper is appropriate for long term service life prediction of concrete structures exposed to chloride containing environment.